Electrical movement for loud-speakers



. Nov; 18, 1936 M; c HOPKINS 1,782,094v

ELECTRICAL MOVEMENT FOR LOUD SPEAKERS Filed Jan. 7, 1927 INVENTOR Marcus C. Hop Kins Bl' 6M4. PM rz 4 ATTORNEYS Patented Nov. 18, 1930 UNITED STATES PATENT OFFICE Q MARCUS C. HOPKINS, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR, BY MESNE A$SIGNMENTS, TO HOPKINS CORPORATION, OF JERSEY CITY, NEW JERSEY, A COR- PORATION OF DELAWARE ELECTRICAL MOVEMENT FOR LOUD-SPEAKERS Application. filed January 7, 1927. Serial No. 159,552.

. This invention relates to improvements in telephone instruments generally and more particularly to the operating mechanism of loud speaking telephones.

In the loud speaking type of telephone instrument it is the usual practice to employ an electrical unit embodying a permanent magnet, current carrying coils and an armature whereby the armature is oscillated, and to translate the oscillations of the armature into sound by a mechanical connection between the armature and a diaphragm. In associating the permanent magnet of such structures with the current carrying coils considerable difficulty has been encountered due to the fact that the permanent magnet had to be bored, milled or otherwise machined to facilitate its assembly with the other parts of the unit.

With these facts in mind thepresent invention seeks to provide means for associating the permanent magnet and coils of a telephone instrument without the necessity of modifying the form or configuration of the permanent magnet by boring, milling or otherwise machining, as has heretofore been the practice. To this end the invention contemplates means for readily assembling the permanent magnet and coils of such an instrument, and maintaining the same in operative relation by means lying entirely outside of the body of the magnet, in contradistinction to those constructions which employ means passing through the body or stock of the magnet.

Another object of the invention is to provide means for adapting the coils to permanent magnets of different sizes and dimensions, said means including adjustable attaching elements which do not traverse or contact with the body 'of the permanent mag net.

Another object of the invention is to mount the armature of the structure in a manner such that a direct connection may be provided between the armature and the diaphragm of the instrument.

These and other objects of the invention will become apparent from the following sembled unit.

specification read in connection with the accompanylng drawing wherein Figure 1 1s a perspective view of the as- Fig. 2 is a sectional View taken on the line 2-2 of Fig. 1.

Fig. 3 is an elevation partly in section, taken on the line 3-3 of Fig. 2.

Fig. 4 is a sectional View, taken on the line 44 of Fig. 3.

but it is of .course apparent that the magnet may be circular, horse shoe or otherwise in configuration, as found desirable. The legs 'l and'l of the magnet 1 are provided with pole pieces 3 and 4, respectively, said pole pieces being magnetically connected with their respective legs of the magnet, by means of iron blocks 5 and 6 inserted between the pole pieces and magnet, the opposite ends of each pole piece being separated and spaced from the other leg-of the magnet 1 by means of brass or other non-magnetic inserts 7 and 8, corresponding in size and thickness to the iron blocks 5 and 6.

The pole pieces 3 and 4 and the blocks 5, 6, 7 and 8 interposed between the pole pieces and magnet are all clamped securely together by means of transverse connecting bolts 9.

otherwise machining the magnet 1 to accombers are fixedly secured to the pole piece 3 in an obvious manner. The pole piece 4 is provided with apertures 15 and 16, alined respectively with the core members 10 and 11, said apertures being provided with fibre rings or bushing 17, whereby to separate the core members from the pole piece 4. By this construction it is apparent that the core members 10 and 11 cooperate to form a complete metallic magnetic circuit for the magnet 1 with the exception of the gaps defined by the fibre insulating rings 17. It is important in this connection to note that the air gaps between'the cores 10 and 11 and the pole piece 4 as defined by the fiber rings 17 should be somewhat greater than the normal gap existing between the ends of the core members and the armature member, so that the active flux will operate across the latter gaps.

Upon the core members 10 and 11, the coils 2 are conveniently mounted, said coils being preferably wound in reverse direction relative to one another. The core members 10 and 11 also serve as a convenient'support for a block 20 of insulating material, upon which are mounted suitable binding posts 21 and 22, said binding posts being adapted to receive conductors communicating with a radio receiving set or other source of signal energy. The block 20 may be appropriately apertured or notched as at 18 and 19 to accommodate the fastening bolts 9.

The free ends of the cores 10 and 11 are designed to lie substantially flush with the plane of the outside surface of the pole piece 4 which relation may be easily brought about by reason of the adjustability of the nuts 13 and 14'cn the core members 10 and 11. Operatively associated with the core members is an armature 23 mounted upon the pole piece 4by means of a y oke or bridge piece 24 shown more clearly in Fig. 5. The armature 23 is supported by said yoke 24 in spaced relation with respect tothe pole piece 4 and the free ends of the core members 10 and 11.. WVhile the armature supporting member 24 may be made in any convenient form, a preferred design is shown in the present instance as an E-shaped blank having the baclr or yokeportion 25 thereof bent at substantially right angles to the plane of the arms. Tl11S construction is clearly shown in Fig. 5, where n wease the back or yoke portion 25 and the arms 26 and 27 are shown occupying planes at substantially right angles to each other. As shown in Figs. 1 and 2, the armature supporting bridge 24 is secured to the pole piece 4, transversely thereof by means of suitable screws or rivets 28, the legs 26 and the pole piece 4 being suitably apertured for this purpose. The arm 27 which functions to support the armature 23.,is displaced slightly from the plane of the arms 26, so that when the bridge is mounted upon the pole piece 4, said arm 27 will lie in a plane parallel to, but spaced slightly from the plane of the pole piece 4, this for the purpose of maintaining a slight air gap between the armature 23 and the ends of the core pieces 10 and 11. As shown, the arm 27 and the armature 23 are suitably apertured to provide means for readily securing the armature to the bridge.

It is to be noted in this connection that the bridge member 24 is preferably made of substantially resilient material, whereby the arm 27 will possess sufficient inherent resiliency to maintain the armature in substantial parallelism with the pole piece 4 and to retract the armature to such position from an attracted position adjacent the pole piece 4 when the direction of the flux in the circuit reverses,

The operation of the device will be apparent from the foregoing description.

WVhen no current is passed through the coils is intensified while that of the other is counter-acted or neutralized thus causing an increased attraction on one end of the armature and a neutralization of the attraction on the other end causing the armature to vibrate. A reversal of the current in the coils alternately causes the opposite ends of the magnet to be attracted toward the adjacent core member.

It is also apparent that the construction as above outlined provides a ready and easy means of providing a direct connection between the armature 23 and the diaphragm, such connection being indicated at 29.

In conclusion, therefore, it is apparent that I have provided a simple, but secure means for associating in operative relation the permanent magnet and coils of a telephone instrument and this without the necessity of boring, milling or otherwise machining the body or stock of the permanent magnet.

i ture thefixed air 1 1 may be so disposed thereon to accom- FurthermoreQthe arrangement of the armature with to the magnetic structure is such that at each oscillation of the armagap in thecmagnetic circuit of the instrument is bridged by the metal of the armature, thus establishing a complete metallic magnetic circuit, thereby rendering a more powerful and positive impulse to the armature and diaphragm. It is also apparent that by providing the core members 10 and 11 With the screw threads 12, the nuts modate differently dimensioned permanent magnets, and still maintain the proper relation between the cores 10 and 11 and the pole piece 4.

While, I have chosen to illustrate and describe a preferred embodiment of my invention, it is to be understood that such illustration and description is for the purpose of example only, and not as defining the limits of my invention which are to be determined from the scope of the appended claims.-

Having thus described my invention what I claim as new is:

' 1. A telephone instrument comprising a permanent. magnet, a pole piece connected to each pole of the permanent magnet, the

pole pieces being arranged substantially parallel to each other, a pair of reversely wound coils aranged between said pole pieces, core the path for the magnetic flux, and being spaced from the other pole piece, and an armature carried by said second pole piece in operative relation with the ends of said core members, Y

4. A telephone instrument in accordance with claim 1 wherein the armature is arranged in a plane substantially parallel to the plane of the ends of the core members and spaced therefrom to form airgaps, said armature being pivotedintermediate its ends.

5. A device in accordance with claim 1 wherein a bridge member is arranged on the outer side of said second pole piece to form a support for said armature and said arma- MARCUS C. HOPKINS.

ture is pivoted intermediate its ends on said elements for said coils, said core elements .being connected to one of saidpole pleces to form aportion of the path for the magnetic flux, and being spaced from-the other pole piece, and an armature carried by said second pole piece in operative relation with the ends of said core members.

2. A telephone instrument comprisinga permanent magnet, a pole piece connected to each pole of the magnet, said pole pieces being arranged on opposite'sides of the permanent magnet and substantially parallel to each other, apair of reversely wound coils arranged between saidpole pieces,core elements for said coils, said core'elements being connected to one of said pole pieces to form a portion of the path for the magnetic flux and being spaced'from the other pole piece, and an armature carried by said secondpole piece in operative relation with the ends of said core members. I

3. A telephone instrument comprising a I permanent magnet, a pole'piece connected to each pole of the magnet, the pole pieces being arranged on opposite sides of the magnet and substantially parallel to each other,

each pole piece being separated from its pole by a block of magnetic material and being separated from the other pole of the magnet by a block of non-magnetic material, a pair of reversely wound coils arranged between said pole pieces, core elements for said coils, said core elements being connected to one of said pole pieces to form a portion of 

